From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Causes and remedies for servo judders on a Wraith model.
| Identifier | ExFiles\Box 108\1\ scan0317 | |
| Date | 9th February 1938 | |
| S00a Rm{William Robotham - Chief Engineer}/IMW.{Ivan M. Waller - Head of Chateauroux} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} Rm{William Robotham - Chief Engineer}/AFM{Anthony F. Martindale}1/R.9.2.38. WRAITH 26.G.VI - SERVO. We understand that you have telephoned to say that the servo on 26.G.VI is juddering badly. As we are not on the job, we can only say in general terms what the cause may be. We have had servo judders on two occasions on one Wraith, each time the trouble was water in the servo due to running through floods without undersheets. Servo judders may be of 2 kinds, viz., (1) High Frequency judders, nearly a squeak. (2) Low " " case (1) the trouble is a faulty servo lining, due either to excessive heating (35° cams) or possibly water or oil; case (2) is usually mis-set rods, or again water inside the servo. If the liner is faulty through glazing, or other reason, it may be sandpapered, but we enclose 2 new Halo 3L discs which are giving satisfaction on 24.G.VI. The output from them is normal. Water may be removed by dismantling servo and drying, the discs may be dried in a cool oven. Oil may be removed from V.M.30 discs by Tri-chlorethelene, or, failing that, clean petrol. If oily, we advise fitting the Halo 3L discs (N.B. you have Halo 2L on 6.B.IV.) Mis-set rods are the usual cause of servo judders, i.e. slack behind the servo pick up link. We enclose a pre-print of instructions for setting Wraith brakes to assist you, if this is necessary. On 6.B.IV. we have a "pull on" spring on the servo pick up link to rear brakes which is most effective in stopping mechanical servo judders. We are going to rig up a similar device on Wraith, and send you the pieces. If you fit the Halo 3L discs, keep the writing away from the rubbing face. The output from the servo may be poor at first as the discs are bound to be handled in transit. Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} | ||